You are showing your lack of connection to the modern games scene in a few places, though.

Hey, I was half expecting to be told such a game already exists. ;-)

a really successful group of players is pretty much indistinguishable from a band.

There are rumors that the Guitar Hero franchise may actually move in more or less this direction.

Makes sense. If they set it up so that bands can play together over the Internet (not a trivial problem, because of clock skew), then they could wind up with bands forming that couldn't have otherwise. Add in a way to publish the resulting music, and they'll have created something huge.